logging the simulation

[Albert Solernou Crusat]

Currently, measurement_out, which is an array of files, has a file measurement file for each blob, and then a last one, measurement_out[num_blobs], for the "measurement_world" file.

We should log there, not only the simulation steps, but also: - a time stamp. - the list of USED parameters.

[Albert Solernou Crusat]

done!